• Proceedings of the KSAR Conference
• /
• 2001.03a
• /
• pp.76-76
• /
• 2001

The objective of this study was to optimize the vitrification method of in vitro produced bovine embryos. Thus, in vitro produced embryos at 8 cell, morula and blastocyst stages were vitrified on electron microscope grids (EM grids) or in open pulled straws (OPS) with EG5.5 (5.5 M ethylene glycol, 1.0 M sucrose and 10% FBS in m-DPBS medium) freezing solution and their survival rates after thawing were compared. The embryos on EM grids or in OPS were briefly exposed to EG5.5 freezing solution and plunged directly into liquid nitrogen within 30 to 35 sec. Post-thawed embryos were serially diluted in 0.5, 0.25 and 0.125 M sucrose in m-DPBS, each for 1 min, and then cultured in CRI aa medium supplemented with 10% FBS. Embryonic survival rate was assessed as re-expanded and hatched rates of those embryos after warming. The rates of re-expansion embryos did not significantly different between EM grid (8 cell: 42.10%, morula: 66.66% and blastocyst: 77.08%) and OPS (8 cell: 47.36%, morula: 61.90% and blastocyst: 83.33%) methods. In addition, the hatched rates in EM grid (8 cell: 31.57%, morula: 57.14% and blastocyst: 72.91%) were similar to those in OPS (8 cell. 34.21%, morula: 50.00% and Blastocyst: 77.08%). Interestingly, even at the same blastocyst stage, the in vitro survival of day 7 embryos (EM grid: 79.48 and OPS: 87.18%) was higher than those of day 8 embryos (EM grid: 72.10 and OPS: 82.06%). The total cell number of blastocyst developed in vitro after vitrification was examined with Hoechst 33342 staining to compare the embryo quality among different treatment groups. The total cell number of blastocyst was not significantly different between vitrified groups (EM grid: 162.4$\pm$8.0 and OPS: 158.4$\pm$7.1) and unvitrified control (168.0$\pm$5.6). These results indicate that both vitrification containers can provide the high rate of embryo survival. Moreover, the OPS container may not need a cap to protect the container from floating after immersion in L$N_2$. Therefore, this study suggest that bovine embryos can be cryopreserved easily, effectively and successfully by vitrification method using EM grid or OPS with EG5.5 freezing solution. In the future, the Pregnancy rate would be investigated after transfer of our vitrified embryos into the appropriated recipients.

• Design & Manufacturing
• /
• v.17 no.1
• /
• pp.20-26
• /
• 2023

Lab-on-a-disc is a circular disc shape of cartridge that can be used for blood-based liquid biopsy to diagnose an early stage of cancer. Currently, liquid biopsies are regarded as a time-consuming process, and require sophisticated skills to precisely separate cell-free DNA (cfDNA) and circulating tumor cells (CTCs) floating in the bloodstream for accurate diagnosis. However, by applying the lab-on-a-disc to liquid biopsy, the entire process can be operated automatically. To do so, the lab-on-a-disc should be designed to prevent blood leakage during the centrifugation, transport, and dilution of blood inside the lab-on-a-disc in the process of liquid biopsy. In this study, the main components of lab-on-a-disc for liquid biopsy are fabricated by injection molding for mass production, and ultrasonic welding is employed to ensure the bonding strength between the components. To guarantee accurate ultrasonic welding, the flatness of the components is optimized numerically by using the response surface methodology with four main injection molding processing parameters, including the mold & resin temperatures, the injection speed, and the packing pressure. The 27 times finite element analyses using Moldflow® reveal that the injection time and the packing pressure are the critical factors affecting the flatness of the components with an optimal set of values for all four processing parameters. To further improve the flatness of the lab-on-a-disc components for stable mass production, a quarter-disc shape of lab-on-a-disc with a radius of 75 mm is used instead of a full circular shape of the disc, and this significantly decreases the standard deviation of flatness to 30% due to the reduced overall length of the injection molded components by one-half. Moreover, it is also beneficial to use a quarter disc shape to manage the deviation of flatness under 3 sigma limits.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.22 no.2
• /
• pp.121-127
• /
• 1977

Leaf burning due to nitrofenapplication was characterized as brown color spot appearing on the leaf sheath and blade. The spots predominantly appeared around 5-7 cm high above soil surface regardless of different particle size, formulation, application method, or water level. Magnitude and frequency of burn spots increased somewhat as the granular size gets finer, by higher water level, or in transplanted rice compared to directly sown rice when applied at 7 leaf-stage, but there was no indication of increase in leaf burning due to clinging of floating dust to rice plant. When collections from local distributor's stock of TOK 7G, a granular formulation of nitrofen, were analyzed for particle size composition, 98.9% by weight ranged between 9 to 35 meshes, and only about 0.08% by weight was of particles finer than 100 mesh.

• Journal of the Korea Society of Computer and Information
• /
• v.28 no.8
• /
• pp.175-186
• /
• 2023

In this paper, we aim to build a gentrification analysis model and examine its characteristics, focusing on the point at which rents rose sharply alongside the recovery of commercial districts after the gradual resumption of daily life. Recently, in Korea, the influence of social distancing measures after the pandemic has led to the formation of small-scale commercial districts, known as 'hot places', rather than large-scale ones. These hot places have gained popularity by leveraging various media and social networking services to attract customers effectively. As a result, with an increase in the floating population, commercial districts have become active, leading to a rapid surge in rents. However, for small business owners, coping with the sudden rise in rent even with increased sales can lead to gentrification, where they might be forced to leave the area. Therefore, in this study, we seek to analyze the periods before and after by identifying points where rents rise sharply as commercial districts experience revitalization. Firstly, we collect text data to explore topics related to gentrification, utilizing LDA topic modeling. Based on this, we gather data at the commercial district level and build a gentrification analysis model to examine its characteristics. We hope that the analysis of gentrification through this model during a time when commercial districts are being revitalized after facing challenges due to the pandemic can contribute to policies supporting small businesses.

• Journal of the Korean Geotechnical Society
• /
• v.39 no.3
• /
• pp.5-16
• /
• 2023

The effect of raft flexibility on piled raft foundations in sandy soil was investigated using a numerical analysis and an analytical study. The investigation's emphasis was the load sharing between piles and raft following the raft rigidity (K_R), end-bearing conditions. The case of individual piles and subsequently the response of groups of piles was analyzed using a 3D FEM. This study shows that the α_pr, load-sharing ratio of piled raft foundations, decreases as the vertical loading increases and as the K_R decreases. This tendency is more obvious when using friction piles compared to using end-bearing piles. The effect of raft rigidity is found to be more significant for the axial force distribution - each pile within the foundations has almost similar axial forces of the pile head with a flexible raft; however, each pile has different values with rigid rafts, especially with the end-bearing piles. The axial force of the pile base with floating piles shows similar point-bearing resistance for all the piles; however, it shows different values with end-bearing piles. The differential settlement ratio of rafts showed a larger value with lower K_R.

• Fisheries and Aquatic Sciences
• /
• v.25 no.12
• /
• pp.626-636
• /
• 2022

Shellfish are exoskeleton-bearing aquatic invertebrates that consume various organic and inorganic substances floating in seawater through filter feeding. Heavy metals are known as absorbed and accumulated in seawater. Some of the toxic heavy metals are highly accumulated in seawater, and exposure to them can cause a variety of risks to the human body. Since Koreans like to eat seafood, they are more likely to be exposed to contaminated seafood with heavy metals. In this study, nine types of heavy metals were analyzed on ten different shellfish species in the coastal area of South Korea. The risk assessment was also done on shellfish in which heavy metals were detected. Zinc (Zn) and copper (Cu) were identified at an average of 56.7 mg/kg (6.70 to 466 mg/kg) and 13.2 mg/kg (0.064 to 143 mg/kg), respectively. Lead (Pb) average of 0.208 mg/kg (0.000750 to 1.02 mg/kg), cadmium (Cd) average of 0.454 mg/kg (0.0388 to 1.56 mg/kg) and mercury (Hg) average of 0.0266 mg/kg (0.00548 to 0.174 mg/kg) were identified. Additionally, arsenic (As), chromium (Cr), nickel (Ni), and silver (Ag) were also identified as average concentrations of 4.02 (0.460 to 15.0 mg/kg), 0.167 (< limit of quantification [LOQ] to 0.820 mg/kg), 0.281 (< LOQ to 1.46 mg/kg), and 0.158 mg/kg (< LOQ to 1.15 mg/kg). The result indicates that the monitoring results of heavy metals in most shellfish satisfied the Korean standard. However, Pb and Cd have exceeded some foreign standards, such as the United States and the EU. The permissible human exposure calculated using the heavy metal intake and detection amount was lower than the Joint FAO/WHO Expert Committee on Food Additives human safety standard, and the risk of heavy metals from shellfish consumption was at an acceptable level.

• Journal of Wetlands Research
• /
• v.25 no.2
• /
• pp.83-90
• /
• 2023

Due to climate change, the occurrence of abnormal rainfall is increasing, and the intensity and scale of damage caused by heavy rain are increasing every year. In addition, as the frequency of heavy rains becomes more frequent, heavy rains often occur continuously, resulting in large flooding damage that has never been seen before in urban area. When near rivers and coastal areas are impermeable areas, the maximum flow increases rapidly as the rainfall intensity increases, so a comprehensive flood risk evaluation is needed considering the characteristics of the basin. In this study, the flood inundation risk evaluation was analyzed by giving scores on evaluation factors as a measure to prevent inundation in subway stations. Through the flood inundation risk evaluation process considering the comprehensive evaluation index, the flood risk evaluation was conducted on five urban railway stations with a large amount of traffic and floating population that had been inundated in the past. It is judged that by comprehensively analyzing this and establishing a inundation risk grade (grade 1 to 4) to establish a flood measure suitable for the risk grade.

• Journal of architectural history
• /
• v.32 no.3
• /
• pp.7-20
• /
• 2023

The compositions of ethnic groups in Macau vary with time. Prior to the opening of the port, the majority of the residents in Macau were Chinese people, including those living on land and at sea. After the port was opened, with the increase of Portugal businessmen and missionaries, the population was divided into Chinese people and foreigners (so-called 'Yiren' or 夷人 in Chinese). Chinese people living on land were mainly of Hakka, Fujian, and Cantonese descent. Those living at sea were referred to as 'Tanka People' (named 'Danmin' or 蜑民in Chinese). They lived on floating boats for their entire lives and were similar to the 'drifters' in Japan. Since modern times, many refugees from mainland China and Southeast Asia flooded into Macau due to warfare. The development of industrialization required a larger number of laborers, and some 'coolies' entered Macau in legal or illegal ways, making it a multi-ethnic city. However, the Tanka people were not considered a minority ethnic group under the national ethnic policy of 56 ethnic groups since they did not have an exclusive language and shared dialects in different regions. As the ports inhabited by Tanka people gradually restored foreign trade, the boats and stilt houses used by Tanka people were dismantled to expand the infrastructure area of the ports. Many Tanka people began to live on land and marry people on land, leading to the disappearance of the Tanka group in Macau. The fishing boats and stilt houses used by Tanka people have also disappeared, with only a few remaining in areas such as Pearl River Delta and Hong Kong. This paper examines the natural and social environment of Tanka people in Macau from the Ming and Qing dynasties to the Republic of China, as well as the adaptive changes they adopted for the aforementioned environment in terms of living space and architectural type, on the basis of summarizing the historical activities of Tanka people. Finally, this study provides a layout plan and interior structure of the most commonly used boat for Tanka people from the Ming and Qing dynasties to the Republic of China, with the use of CAD and other technical software, along with reference to written historical documentation, and provides a case study for further research on the architectural history of Macau's inner harbor cities, from anthropological and folklore perspectives.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.233-233
• /
• 2020

최근 우리나라의 2030년 10GW의 농촌 태양광 보급목표 달성을 위해 전국적으로 분포하고 있는 저수지 및 댐 등의 공유 수면을 활용한 수상태양광 설치가 적극 검토되고 있다. 수상태양광 사업의 증가와 함께 수상태양광 설치 및 운영이 환경적 측면에서 논쟁이 대두되고 있으나 수상태양광 발전시설이 호소 수생태계에 미치는 영향을 판단할 수 있는 장기적인 조사나 과학적 연구가 부족한 실정이다. 본 연구에서는 저수지에 설치되어 있는 수상태양광 발전시설에 의한 수생태계에 미치는 영향을 파악하기 위해 수상태양광이 운영되고 있는 2개소의 저수지를 대상으로 식물플랑크톤, 동물플랑크톤, 저서성 대형무척추동물, 어류 군집조사를 2개년(2017~2018년) 동안 실시하여 각각의 종풍부도 및 종다양도 지수를 분석하였다. 1차년도에는 수상태양광 패널 설치지역 및 패널로부터 200~250m로 이격거리를 유지하면서 총 6지점을 조사하였으며, 2차년도에는 수상태양광 패널 하부(영향권) 3지점과 패널로부터 약 250m 이격된 2지점(비영향권)을 대상으로 총 6회의 조사를 수행하였다. 식물성플랑크톤, 동물성플랑크톤, 저서 대형무척추동물, 어류 군집에 대한 종풍부도와 종다양성에 대한 분석결과, 종풍부도 및 종다양도는 발전시설 영향권 지역과 비영향권 지역간에 통계학적으로 유의미한 차이는 없는 것으로 나타났다. 종풍부도는 수상태양광 패널로부터 이격거리가 멀어질수록(열린수역으로 향할수록) 감소하는 수치를 보이다가 저수지 수변부에 가까워지면 높아지는 경향을 나타났다. 종다양도 역시 종풍부도 결과와 유사하게 수상태양광 패널 지역으로부터 이격거리가 증가함에 따라(열린수역으로 향할수록) 지수가 감소하다가 저수지 수변부에 가까울수록 높아지는 결과를 보였다. 이러한 결과는 동식물성 플랑크톤과 저서생물 및 어류 군집의 종풍부도, 종다양도가 수상태양광의 영향권과 비영향권간에 큰 차이를 없음을 나타내고 있으며, 일부 분류군의 경우 열린 수면보다 수상태양광 설비에 의한 반 폐쇄수역에서 종풍부도와 종다양도가 오히려 높게 나타났다. 그러나 본 연구결과는 설치된 수상태양광 패널이 전체 수면의 5% 미만에 해당하는 소규모 시설이므로 본 연구결과를 일반화해서 해석하기에는 한계가 있다. 넓은 수면적에 설치되어 있는 대규모 시설 및 20년 이상 장기간 운영되는 수상태양광 발전시설을 대상으로 지속적인 모니터링 및 누적된 환경영향 평가가 필요할 것으로 판단된다.

• Convergence Security Journal
• /
• v.22 no.4
• /
• pp.11-16
• /
• 2022

Development of science technology make integrated CPS(Cyber-Physical System) appear. In CPS era, cyberspace and physical-space are hard to separate anymore, that is developing toward integrated CPS. The reality is not stopping, that is consistently changing and the concept of space is developing too. But several articles are considering for cyberspace and physical-space separately, and they are developing tailed alternative each case. The theorical approaching that is not considering reality is dwelled on past, and is dangerous from dropping down to floating cloud that is not considering progressed reality. This article is suggested to consider rimland theory to control measures in cyberspace. That is dedicated to integrated approaching from physical-space to cyberspace. And that is developing concreted controling measures in cyberspace. Especially, this article is suggested to policy alternative by analyzing north korea cyber warfare from rimland theory including human sources. Simplicity is the ultimate sophistication. This article make integrated approaching effects about cyberspace and physical-space to preparing in the CPS era.